JPS6017841A - Crt - Google Patents

Abstract

PURPOSE:To eliminate a change of the resolution due to the angle of incidence of an electron beam and prevent the occurrence of the resolution irregularity by inclining a phosphor screen against the center axis of the beam and making the curve shape facing the beam on the cross section of the phosphor sereen a logarithmic spiral curve with the deflection center serving as the origin. CONSTITUTION:A phosphor screen 7 is inclined against the center axis 9 of a beam, and the curve shape facing the beam on the cross section of the phosphor screen 7 is made a logarithmic spiral curve (l) with the deflection center A serving as the origin. Thereby, the angle of incidence of the electron beam to all points on the phosphor screen from the deflection center is made completely constant, the resolution can be made completely equal over the whole area of the phosphor screen, thus an excellent image with no resolution irregularity can be obtained.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a cathode ray tube.

(b) Prior Art Generally, cathode ray tubes used in television receivers, etc., have an electron gun placed on an axis perpendicular to the fluorescent surface, and irradiate the fluorescent surface with an electron beam through a metal backing film. scanning.

Therefore, the head of the cathode ray tube becomes larger and the depth becomes longer, so the receiver itself, which is roughly determined by each floor based on the area of the cathode ray tube's fluorescent surface and its depth, also becomes larger. This is a major problem when configuring.

For this reason, it is a flat type that has a fluorescent surface inclined with respect to the central axis of the beam, and there is almost no difference in the diameter of the beam traveling distance (two-way spot v), and there is almost no change in resolution due to the difference in traveling distance. Cathode ray tubes have been devised, but in such a case, the angle of incidence of the beam on the phosphor surface has a significant effect on the resolution.

One method to solve this problem is proposed in Japanese Patent Publication No. 41-5294. In this case, the incident angles of the electron beam at both ends of the fluorescent surface can be made equal; The angle of incidence at the center of the optical surface can only be approximately equalized, and this cannot be said to be a sufficient solution to completely eliminate changes in resolution.

(/→ Purpose of the Invention It is an object of the present invention to provide a cathode ray tube which eliminates the problem in the prior art described above, that is, the change in resolution due to the angle of incidence of the electron beam, and which has an f2 resolution without causing any unevenness in resolution.

4. Structure of the Invention The cathode ray tube of the present invention has a fluorescent surface inclined with respect to the central axis of the beam, and the curved shape of the side facing the beam in the cross section of the fluorescent surface is a logarithmic spiral curve whose origin is the deflection center. I have to.

Body) Example Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, (1) is a flat glass tube, and an electron gun (3) is enclosed inside a neck portion (2) of the tube (1), and a deflection coil ( 4) is installed. Further, (5) is an anode cavity, (6) is a conductive film layer, and (7) is a fluorescent surface provided inside the conductive film layer (6).

That is, the fluorescent surface (7) having a certain angle with the Nevk part (2) is aligned with the central axis (9) of the electron beam (8) when it is not deflected.
), the back side of the fluorescent surface υ far from the electron gun should be close to the beam center axis, and the beam center axis (9
) and provided on one side, and the fluorescent surface (7) is provided inside the bottom part 101 of the flat glass tube (1) so that the electron beam directly hits the fluorescent surface (7). It is being (11) is a transparent conductive thin film surface formed on the inner surface of the flat glass tube (corresponding to the fluorescent surface (7) of 11), and its potential is generally set to be the same as or lower than the potential of the anode (7). Also, a'';!J is a centering point for aligning the center of the electron beam with the center of the fluorescent surface (7).
) The electron beam (8) emitted from the deflection coil (4)
The light is deflected by the phosphorescent surface (7) and causes it to emit light, which can be observed through the above-mentioned transparent conductive thin film surface.

In the case of a cathode ray tube having the above configuration, the electron beam (8) produces a trapezoidal raster as shown in FIG. 2 by means of electromagnetic deflection or electrostatic deflection.
This trapezoidal raster U can be corrected into a rectangular raster C2 depending on the shape of the deflection coil, the waveform of the deflection current, the correction magnet, etc.

Next, the shape of the fluorescent surface of the cathode ray tube of the present invention will be explained.

In FIG. 3, (3) is the center of deflection, and the center of deflection (A) is taken as the origin of this coordinate system, which will be considered below in terms of the stock coordinate system. The curve (Jl is a logarithmic spiral curve, and the curve (Jl) is expressed by the general formula Cr=aekθ (a,: constant, e: base of natural logarithm).

(Pl) (Pl) are points on the logarithmic spiral curve (1), and the curve line segment p1p2 is a curve on the side facing the electron beam (electron beam incident side) in the cross section of the fluorescent surface (7). In other words, the traveling distance of the electron beam is the shortest at the (Pl) end than the deflection center (,A), and (P
l) Longest end.

(T+) (Tz) are the respective points (Pl) (Pz
) is a logarithmic spiral curve (the tangent of l).

(ψ1) (ψ2) [ψ1. ψ2〈redundancy/2〕 are each A
The angle between P I (= r + ) and (T1).

The angle formed by APz (xrz) and (T + 7)
Then, these (ψI) (ψ2) are (PM) (P z
) is the angle of incidence of the electron beam on the cross section of the fluorescent surface at c.

By the way, a logarithmic spiral curve is a curve in which the angle between the straight line connecting the curve (an arbitrary point on the curve and the origin fA) and the tangent at that point is constant.

Therefore, if the curved line segment P+Pz is the curved shape of the side facing the electron beam in the cross section of the fluorescent surface (7), the incident angles on both sides 91M of the fluorescent surface are equal (ψ1-92).
Not only that, but also the incident angle of the electron beam from the center of deflection onto the curved line segment P1P2 is constant at every point on the curved line segment PIPZ.

FIG. 4 shows a curved surface (81) formed as a locus of the curved line segment p+pz rotated around the y-axis, and if this curved surface is is taken as a fluorescent surface, every point on the curved surface (S) The angle of incidence from the center of deflection (false) is completely constant. In other words, if a phosphor is spread on this curved surface (s) with a uniform thickness to form a phosphor surface, the angle of incidence of the electron beam on the phosphor surface will be completely constant at every point on the phosphor surface. Assuming that the difference in spot diameter due to the difference in travel distance of the electron beam is small, the resolution can be made completely equal over the entire area of the fluorescent surface. This is not only preferable in terms of image construction, but also in terms of manufacturing and pressure resistance of cathode ray tubes, it is preferable that the flat glass tube body (1) can be formed into a curved surface.

■ Effect of the Invention In the cathode ray tube of the present invention, the fluorescent surface is inclined with respect to the central axis of the beam, and the shape of the curved line on the side facing the beam in the cross section of the fluorescent surface is set at the deflection center as the origin. Since it is a logarithmic spiral curve, the angle of incidence of the electron beam from the center of deflection to every point on the phosphor surface is completely constant, and the resolution can be perfectly (equal to 2) over the entire area of the phosphor surface.
Therefore, a good image without uneven resolution can be obtained.

[Brief explanation of drawings]

The drawings are all related to the present invention; FIG. 1 is a side sectional view of the cathode ray tube, FIG. 2 is a plan view thereof, and FIGS. 3 and 4 each illustrate the shape of the fluorescent surface of the cathode ray tube. This is a diagram for (7)... Fluorescent surface, (Ill... Beam central axis,
(original...center of deflection, (1)...logarithmic spiral curve. Procedural amendment (spontaneous) February 4, 1980 1. Indication of the case 1989 Patent Application No. 125101 2. Invention Name: Cathode ray tube 6, relationship with the case of persons who repair or replace Patent applicant name (188) Sanyo Electric Co., Ltd. 4, Agent address: 2-18-5 Keihan Hondori, Moriguchi City Subject of amendment + 1) of the specification 1 Detailed Description of the Invention-1 and [Brief Description of the Drawings] column. 12) "Figure 2" of the drawing. 6. Contents of amendment +41 The "echelon shape" written in line 14 of section 4 of the specification is corrected to "fan shape." (2) The contents stated in the 15th line of the fourth column of the specification are corrected as follows. This fan-shaped rask 113) is a deflection coil."
... central axis of the beam" 19) ... central axis of the beam"
Correct to. 141 “Figure 2” of the drawings is amended as shown in the attached sheet. that's all

Claims (1)

[Claims] (1) The fluorescent surface is tilted with respect to the central axis of the beam, and the cross section of the fluorescent surface is made into a logarithmic spiral curve whose origin is the deflection center. Characteristic cathode ray tube.